Patent Literature 1 discloses a computer system which can directly transfer movie data from a DVD (Digital Versatile Disc)—ROM (Read Only Memory) interface to a DVD decoder without a main memory. In the computer system disclosed in Patent Literature 1, the DVD decoder has a master transaction control unit which can start an I/O read transaction, and further controls both of the DVD decoder and the DVD interface by a DVD control driver. According to this configuration, movie data is directly transferred from the DVD interface to the DVD decoder without a main memory.
Patent Literature 2 discloses a calculator system which can execute a plurality of input/output commands with respect to a plurality of devices by one input/output command. The calculator system disclosed in Patent Literature 2 starts an input/output operation when an input/output adaptor receives an input/output command from a CPU. The input/output adaptor transfers data specified by a memory unit to an appropriate input/output control device upon data transmission, and transfers data from the input/output control device to a specified area of the memory unit upon data reception. Meanwhile, the input/output control device has a buffer which stores data.
In addition, Patent Literature 3 discloses a storage subsystem which replaces firmware without stopping an operation. In the system disclosed in Patent Literature 3, a CPU allocates a data cache area in a memory area and controls a disk control unit to read data from a logical disk. Further, the CPU stores the read data in the data cache area of the memory area.